[Python] What pointer comparison to use to test if parent node points to my node in the binary...

Edit: I thought self works like this in C++ and Java

I am learning python and was trying to code the delete-node function for a binary tree. I was surprised - Why do '==', 'id' and 'is' pointer comparisons fail in this test of whether parent node points to my node in the binary tree?

class Node:

...

def delete(self, key):
....
if node_to_delete.parent.left == self: // FAIL

if node_to_delete.parent.left is self: // FAIL

if id(node_to_delete.parent.left) is id(self): // FAIL


In the debugger, I can see that the condition fails each time.

But when I use one of the fields to compare, then it works. But this is wrong because it assumes 'key' is unique

if node_to_delete.parent.left.key == key: // OK


from

def delete(self, key):
(found, node_to_delete) = self.search(key)
assert(found == True), f"key to be deleted:{key}- does not exist in the tree"
# your code here
if node_to_delete.left == None and node_to_delete.right == None:
if node_to_delete.parent.left.key == key:
node_to_delete.parent.left = None
print('after deleting left child of parent, node_to_delete.parent.left ',node_to_delete.parent.left)
if node_to_delete.parent.right.key == key:
node_to_delete.parent.right = None
...

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